Re: Social evolution of hominids
ailak@walrus.megabaud.fi
15 Jan 1997 22:52:34 +0200
pcrowley@indigo.ie wrote:
> Orangs do not progress along the ground easily nor do they
> go outside forest. So it's unlikely that they "moved east".
Did they evolve in East Asia?
> What evidence is there on dolphins? Have you references?
Nooo.. I'm a bad paleontologist!
> Early hominid females were very small and probably could not
> run _at_all_. Even if they could, they were extremely bad
> at it. There was NO selection for running capability in
> females for the first two million years and probably none
> thereafter. Your scenario fits the prevailing paradigm, but
> it flies in the face of massive amounts of evidence dating
> from since the 1970's.
What separates an early hominid from the common ancestor?
> How many full adult males were in the group? Was warfare
> prevalent ? - as in chimps and known hominids (i.e. us).
> If so, would a larger group defeat a smaller one? What is
> the maximum number of males supportable in a group based on
> promiscuous sex? I.e. when does the likelihood of an infant
> sharing enough of your genes become so small that its
> survival is not worth your taking risks for its protection?
How could I know? How many males are in a bonobo group? Debra Mckay
said they are promiscuous and the females are continuously receptive.
How many men are in a !kung san group. They are said to be
promiscuous, too.
> You mustn't be a father -- to say this. Most men care
> passionately about their offspring. This is usually quite
> adequate to maintain pairing even after the "in-love" phase
> has passed. Being in-love consumes a lot of energy and is
> necessary only until the first infant(s) start to grow.
Hmm, this kid stuff makes sense. Maybe I fell in 'female-centrism'?
> The inborn mechanisms were designed to be *good_enough* for
> our paleolithic ancestors. Evolution rarely provides more
> mechanisms than are needed. "Fallling in love", the absence
> of any contraception, joint parental devotion to offspring,
> the harshness of the conditions and the social pressures
> within small groups almost certainly meant that monogamy was
> the rule. Generally only children with two good parents in
> a tightly structured society would prosper. They would then
> continue such a "culture". Call it that if you will, but
> don't knock it. It works -- or more precisely -- it worked.
> It's why we're all here.
>
> It's necessary that the sexes be very attractive to each
> other. So it is not surprising that the "cultural"
> mechanisms (that enabled the survival of the species) should
> break down in a radically different environment. That
> breakdown is unlikely to provide good evidence for earlier
> social structures.
I just wonder how promiscuity has worked for !kung san. Did their
environment change radically?
> The concealed estrus and continuous female receptiivity are
> unquestionably long-established features of hominid anatomy.
> What possible function could they have in promiscuous
> groups? It was an evolutionary development. The
> development of monogamy is one explanation for it.
> What's yours?
Let's model a little! Ten males and ten females make a chimp group.
A female comes in heat, and all males mate with her. Let's say
each male mates once a day during ten days. She comes pregnant, has
her baby and lactates, then has a heat again. I do not know how long
is a chimp pregnancy, but let's say the project takes some 6 months
(I think it's longer). So she is in heat twice a year, or less.
Then a mutation appears, and a female is still receptive after her
heat, when she already is pregnant. All males mate with her as
before, once a day, but maybe for a hundred days. Because all males
have mated with her many times, they prefer her very much and are
keen to first save her and her infants.
Her trait becomes prevalent in the group, and soon all females are
receptive throughout the pregnancy and lactating time, or most of
the year. This includes the few days of ovulation which follow in
due time after each pregnancy, twice a year as before. Each male
mates once a day throughout the year, but since there are now ten
receptive females, that's once a day for her, too.
If they are still promiscuous, each male has sex with one female
today and goes to another female tomorrow. They are continuously
interested in the females and stay much closer to them than before.
A male will also rush to save any female, since she is his frequent
sex partner. So all males appear at the stage together.
Evolutionally, each male has a ten percent probability to save his
own progeny as before, but the *chimp* does not think of that. What
makes him attack, is *his* sex mate in danger, and the support of the
'gang' with him. Nothing else has changed. They still live where a
single chimp without weapons has nothing to say, but ten adult male
chimps make a considerable power.
But you say this daily mating made them live as pairs.
I'm not very informed of this anthro stuff. How do the references
say daily mating prevented the males from having sex with the other
females? What prevents gibbon males from having sex with the other
females, if they mate only a few times a year between pregnancies?
Why should a male now rush to save a female who is not his sex mate
and whose progeny with 100% certainty is not his own? If he died
or even became crippled, that would be disastrous for his own
progeny, who were now dependent just on him. How would evolutionary
development explain this?
What possible function the female's continuous receptivity may have
for bonobos? Or dolphins? Or !kun san?
> There are two fundamental questions: 1) How many mature
> males can you have in a promiscuous group? -- I'd say not
> much more than a dozen. 2) When did hominids start having
> groups larger than this? -- I'd say very early on. Larger
> groups would eliminate smaller ones and there would be a
> very strong impulse towards language for the management of
> larger groups. Such an impulse would be virtually absent in
> smaller groups - of chimp size.
The mesolithic and neolithic people of Finland lived in groups
of about 20-25 persons, concluded from the size of their camps.
I have heard that the most efficient committees have 8 to 10 members,
and that this is the number of adult men which is most common in
modern hunter-gatherer groups. No references.
> Paul.
--
Aila Korhonen in Finland ailak@walrus.megabaud.fi
|